Purpose of UA
- Detection of substances excreted in urine reflecting metabolic disturbances
- Detection of intrinsic renal conditions
UA sx
- Abdominopelvic pain
- Flank pain
- Back pain
- Painful or frequent urination
- Changes in urine color
Types of specimens
- Random
- Catheter
- Midstream clean-catch
How is a UA ordered?
- Dipstick
- Dipstick w/ micro
- Complete UA
- Complete UA w/ reflex urine culture
3 components of UA
- Physical: color, transparency, odor, volume
- Chemical: protein, glucose, ketone, bilirubin, pH, blood
- Microscopic: WBCs, RBCs, casts, crystals
Color of urine
- Straw
- Red
- Amber
What do RBCs in urine indicate?
- Infection
- Urolithiasis
- Neoplasm
- AKI
What do WBCs in urine indicate?
- Infection
- Renal inflammatory processes: interstitial nephritis
What does renal epithelial indicate?
- AKI
- nephritic syndrome
What does squamous cell indicate?
Contamination
What do oval fat bodies indicate?
- Nonspecific
- Nephrotic syndrome
Urinary casts
- Urinary protein forms fibrils that attach to epithelial cells, lining tubule of lumen
- Fibrils may intertwine to form casts
- Casts are eventually washed out of their point of origin & appear in urine
- Cylindrical, cigar-shaped bodies
- Unique to the kidney
Tamm-Horsfall glycoprotein
- Major protein constituent of normal urine (often forms the common matrix of casts)
- Major defense protein of urothelium against bacteria
- Strips do not detect, bc it is so heavily glycosylated
Common urinary casts
- Hyaline
- WBC, RBC
- Granular
- Renal tubular epithelial cell
- Waxy
- Broad
Abnormal urinary crystals
- Found at acidic pH
- Require confirmation
- Antibiotics
- Amino acids
- Altered metabolism
- Radiographic contrast media
Culture indications
- Suspicion of complicated infection*
- Presentation suggestive of pyelonephritis
- Failure to respond to initial therapy, raising possibility of a resistant organism
- Recurrent sx (less than 1 month) after tx of a previous UTI for which no culture was performed
What is the most specific dipstick test to identify infection?
Nitrite
- Product of nitrates
What does specific gravity indicate?
Hydration status
- High # = highly concentrated = dehydration
What does glucose indicate?
Likely due to diabetes
What does blood indicate?
- Menstruation
- Infection
- Kidney stones, AKI
What does protein indicate?
- AKI
- CKD/nephropathy (DM, HTN)
